I don't know your mother or if she raised you, but if she did, she would probably feel that she made a number of efforts that were worthwhile and that made use of her motherly instincts. People loosely make this argument that a same-sex couples can raise children just fine. I think it's a reach. Try asking children or yourself if you would have preferred same-sex parents. Since this has been brought up, I'll just go ahead and say it: is that habit or predisposition of yours really conducive to creating an environment for raising children? Is the issue of marriage equality really just about your rights as an individual? Or does your responsibility as a parent go beyond just you as an individual and affect future generations? Maybe you don't want to adopt or raise children and you just want to live that lifestyle. That's fine, but why should the legal definition of marriage, which affects society as a whole, be altered to accommodate your desires? Your argument seems to be--"Well, heterosexual couples can also have bad marriages, adulterous affairs, and questionable parenting habits too, so why can't we do what we want to do and be legally married?" It's like your argument hinges on the institution of traditional marriage failing so as to accommodate what you want to do.
Again, it's just my opinion and I respect your right to voice yours, but to me this issue isn't even close.